Enzyme quantification

Abstract

The invention generally relates to methods for quantifying an amount of enzyme molecules. Systems and methods of the invention are provided for measuring an amount of target by forming a plurality of fluid partitions, a subset of which include the target, performing an enzyme-catalyzed reaction in the subset, and detecting the number of partitions in the subset. The amount of target can be determined based on the detected number.

1 - 20 . (canceled) 
     
     
         21 . A method for detecting a condition in a human, the method comprising:
 forming fluid partitions comprising components of a chemical reaction;   conducting said chemical reaction;   determining a distribution of at least one product of said chemical reaction;   comparing the distribution to an expected distribution of said product; and   identifying the presence of said condition if said distribution is statistically-significantly different than said expected distribution.   
     
     
         22 . The method of  claim 21 , wherein said product is a protein. 
     
     
         23 . The method of  claim 22 , wherein said protein is beta amyloid protein. 
     
     
         24 . The method of  claim 23 , wherein said distribution is measured as an aggregate of said beta amyloid protein. 
     
     
         25 . The method of  claim 21 , wherein at least one of the components of the chemical reaction comprises a detectable label that is acted on by the chemical reaction. 
     
     
         26 . The method of  claim 25 , further comprising the step of identifying fluid partitions that contain released detectable label. 
     
     
         27 . The method of  claim 25 , wherein the components comprise an enzyme and at least one substrate of the enzyme. 
     
     
         28 . The method of  claim 27 , wherein the enzyme catalyzes a reaction that results in release of a detectable label from the substrate. 
     
     
         29 . The method of  claim 28 , wherein the determining step comprises quantifying an amount of enzyme in the fluid partitions. 
     
     
         30 . The method of  claim 29 , further comprising determining a number of enzyme molecules within each partition based upon signal strength of the detectable label. 
     
     
         31 . The method of  claim 25 , wherein the determining step is based upon a localized concentration of the detectable label. 
     
     
         32 . The method of  claim 31 , wherein the localized concentration is detected within a fluid partition. 
     
     
         33 . The method of  claim 21 , wherein the fluid partitions are droplets. 
     
     
         34 . The method of  claim 33 , wherein the droplets are surrounded by an immiscible carrier fluid.